Sheet metal processing process flow
With the development of today's Society, the sheet metal industry has also developed rapidly. Now sheet metal is involved in all walks of life. For any sheet metal piece, it has a certain processing process, that is, the so-called process flow. To understand the process flow of sheet metal, the first thing to know is the selection of sheet metal materials.
Selection of materials
Sheet metal plus commonly used materials are cold-rolled plate (SPCC) , hot-rolled plate (SHCC) , galvanized plate (SECC, SGCC) , copper (CU) brass, copper, beryllium copper, aluminum plate (6061,6063, hard aluminum, etc.) , aluminum profile, stainless steel (mirror, wire drawing surface, fog surface) , according to the role of different products, choose material is different, need to consider from its use and cost commonly.
1. cold-rolled plate SPCC, mainly used for electroplating and painting parts, low cost, easy forming, material thickness ≤3.2 mm.
2. hot-rolled plate SHCC, material t ≥3.0 mm, also is uses the electroplating, the baking paint piece, the cost is low, but is difficult to form, mainly uses the flat piece.
3. Galvanized Sheet SECC, SGCC. SECC electrolysis plate divides n material, P material, n material mainly does not make the surface treatment, the cost is high, p material uses in the spray coating piece.
4. Copper; mainly used conductive materials, its surface treatment is nickel-plated, chrome-plated, or not for treatment, high cost.
5. Aluminum Plate; General Surface Chromate (J11-A) , oxidation (conductive oxidation, chemical oxidation) , high cost, silver plating, nickel plating.
6. Aluminium Profiles; Pieces of Complex Cross section, used in a wide variety of receptacles. Surface treatment is the same as aluminum plate.
7.Stainless Steel; mainly used without any surface treatment, high cost.
Drawing Audit, in order to compile the process flow of parts, we must know all kinds of technical requirements of part drawing, and drawing audit is the most important part of the process flow of parts.
Drawing Audit, in order to compile the process flow of parts, it is necessary to know all kinds of technical requirements of part drawing, while drawing audit is the most important part of the process flow of parts.
1. Check that the drawing is complete.
2. The relationship of the drawing view, whether or not the marking is clear, complete, marking the size units.
3. Assembly relationship, assembly requirements, key dimensions.
4. The difference between the old and new layout.
5. Translation of pictures in foreign languages.
6. Change the name of the office.
7. Feedback and placement of drawing problems.
8. Materials
9. Quality and process requirements
10. A quality control stamp is required for the official release drawing.
Expansion note, expansion diagram is based on the parts of the MAP (3d) expansion plan (2d)
1. Spread out in a way that is convenient, material-saving and processable
2. Choose the clearance and the way of wrapping reasonably, the clearance below T2.0 is 0.2, the clearance between t2-3 is 0.5, and the way of wrapping is long side wrapping short side (door panel type)
3. Reasonable consideration tolerance shape size: negative difference to the end, positive difference to the half; Hole Size: positive difference to the end, negative difference to the half.
4. Direction of Burr
5. Pull teeth, press rivet, tear, Punch bump (package) , etc position direction, draw section view
6. Check material, plate thickness, to plate thickness tolerances
7. Special Angle, Bend Angle Inside Radius (usually r 0.5) to try to fold and decide to expand
8. Highlight areas that are prone to error (similar asymmetries)
9. Zoom in on larger areas
10. The place to be protected shall be indicated
The technological process of sheet metal processing, according to the differences in the structure of sheet metal parts, technological process can be different, but the total does not exceed the following points.
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Cutting: There are various ways of cutting, mainly in the following ways
①. SHEARING MACHINE: it uses shearing machine to cut strip material. It is mainly used to prepare and process the die for blanking forming. The cost is low and the precision is lower than 0.2, but it can only process strip material or block material without hole and cutting angle.
②. Punch: The use of punch in one or more steps on the plate parts after the parts of the sheet metal stamping forming various shapes of parts, its advantages are short labor hours, high efficiency, high precision, low cost, suitable for mass production, but to design the mold.
③. NC numerical control blanking, when NC blanking, the first thing is to write the NC machining program, using the programming software, the drawing drawing is written into the program which can be recognized by NC numerical drawing machine tool, according to these programs, each component shape plate is punched on the plate step by step, but its structure is influenced by the cutter structure, the cost is low, the precision is 0.15.
④. Laser cutting is a method of laser cutting, which can cut the structure and shape of the plate on the large plate, and need to write laser program as NC cutting. It can cut all kinds of complicated shape of the plate, the cost is high, the precision is 0.1.
⑤. Sawing machine: mainly uses the aluminum profile, the square tube, the drawing tube, the round bar and so on, the cost is low, the precision is low
2. Fitter: COUNTERSUNK, tapping, reaming, drilling
The angle of countersunk hole is generally 120 °C for pulling rivet, 90 °C for countersunk head screw, tapping inch bottom hole.
3.Hemming:
Also known as drawing hole, turning hole, is in a smaller hole on the foundation to draw a slightly larger hole, and then tapping, mainly using sheet metal relatively thin processing, increase its strength and thread circle number, avoid sliding teeth, generally used for sheet metal relatively thin, the normal shallow flanging around the hole has almost no change in thickness. If the thickness is allowed to be thinned by 30-40% , the height of flanging can be 40-60% higher than that of normal flanging height. The maximum flanging height can be obtained if the flanging height is squeezed by 50% , such as 2.0,2.5 or more plate thickness, you can direct tapping.
4. Punch:
Is the use of die forming process, the General Punch processing of punching, cutting, blanking, punching bump (bump) , punching and tearing, drawing hole, forming and other processing methods, its processing needs to have the corresponding mold to complete the operation, such as punching blanking die, punch die, tear die, drawing die, forming die, etc. , the operation of the main attention to the location, direction.
5. Press Riveting:
Pressure riveting on the company, there are pressure rivet nuts, screws, loose, etc. , it is through hydraulic riveting machine or punch to complete the operation, riveting to the sheet metal, there are expansion riveting, we need to pay attention to the direction.
6. Bend;
Bending is turning a 2d flat piece into a d piece. Its processing needs to have the folding bed and the corresponding bending die to complete, it also has the certain bending order, its principle is to the next knife does not have the interference first, will have the interference after the bending.
The number of bending strips is 6 times the thickness of the plate below 3.0 mm, such as: t 1.0, v 6.0 f 1.8, t 1.2, v 8, F 2.2, t 1.5, v 10, F 2.7, t 2.0, v 12,
F=4.0
Folding bed mould classification, straight knife, SCIMITAR (80 °C, 30 °C)
Aluminum Plate Bending, there are cracks, can increase the width of the lower die groove type increase the upper die R (annealing can avoid cracks)
Matters needing attention when bending: I drawing surface, thickness and quantity of plate, II bending direction
III Bending Angle; IV Bending Size; VI appearance, chrome-plated Parts shall not have a crease.
The relation between bending and riveting process is that in general, the material is first pressed and then bent, but after pressing and riveting, it will interfere with the process of bending and then pressing, and some need to be bent like bending and then bending.
7. WELDING:
Welding definition: The atoms and molecules of the material to be welded form a whole from the Jingda lattice distance
Category 1:
A FUSION WELDING: Argon ARC welding, CO2 welding, gas welding, manual welding
B Pressure Welding: spot welding, Butt Welding, impact welding
C BRAZING: Electric Chromium welding, copper wire
2 Welding Mode: A GAS METAL ARC welding
B Argon Arc welding
C spot welding, etc.
D-robot welding
Generally speaking, CO2 Gas metal arc welding is used for welding iron plates; Argon Arc welding is used for welding stainless steel and aluminum plates, and Robot welding can save man-hours, improve work efficiency and welding quality, reduce work intensity.
3 WELDING SYMBOLS: Fillet Welding, , type I welding, type V welding, single side v Welding (v) with Blunt Edge v Welding (V) , spot welding (o) , plug welding or groove welding (FL) , curling welding () , single side v Welding with Blunt Edge (V) , with Blunt U type welding, with blunt edge J type welding, back sealing welding, joint welding
4 Arrow wires and connectors
5 welding defect and its preventive measures
Spot welding: the strength is not enough to hit the bump, the area of forced welding
CO2 WELDING: High Productivity, low energy consumption, low cost, rust resistance
Argon ARC WELDING: Solution Depth, solution speed slow, low efficiency, high production cost, with tungsten defects, but has the advantages of better welding quality, welding Non-ferrous metal, such as aluminum, copper, magnesium and so on.
6 WELDING DEFORMATION REASON: Insufficient preparation before welding, need to add fixture
Improvement Process of welding fixture
Bad welding sequence
7 welding deformation effect method: Flame effect method
Vibration method
Hammer method
Artificial aging
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